Medical implants are used in many areas of medicine to enhance the length and/or quality of the life of the implant recipient. Such implants include pacemakers, controlled drug delivery implants and cochlear implants.
The insertion of such devices often requires surgery, and once in place, it is desirable to not have to replace the device, or if occasional replacement is necessary, the number of replacement procedures should be kept to a minimum.
One major factor in determining whether a patient must undergo surgery again is the secure fixation of the device within the patient. If the device has not been securely fixed in position, it may be necessary to repeat the procedure.
An improperly fixed device can result in less than optimal performance of the device, as well as severe medical consequences for the patient.
It is particularly important to have the device properly fixed in the early post operative stage, before fibrous tissue and bone has formed around the device to assist hi its retention.
The fixation of the implantable device often takes a significant proportion of the time of the surgery, and often necessitates the area around the implant site to be completely open, increasing the severity and risks of the surgery.
It is preferred to perform minimally invasive procedures to minimise the severity and risk of the surgery. One such procedure involves the use of a periosteal pocket, where a smaller incision is made, and the device is slid into the formed pocket between the bone and the tissue.
However, some types of medical implants do not lend themselves to this type of procedure. One such device is a cochlear implant, which is used to treat patients who suffer from hearing loss.
A cochlear implant allows for electrical stimulating signals to be applied directly to the auditory nerve fibres of the patient, allowing the brain to perceive a hearing sensation approximating the natural hearing sensation. These stimulating signals are applied by an array of electrodes implanted into the patient's cochlear.
The electrode array is connected to a stimulator unit which generates the electrical signals for delivery to the electrode array. The stimulator unit in turn is operationally connected to a signal processing unit which also contains a microphone for receiving audio signals from the environment, and for processing these signals to generate control signals for the stimulator.
The signal processing unit is in practice, located externally to the patient and the stimulator is implanted within the patient, usually near the mastoid on the patient's skull and underneath the surrounding tissue. The processor and stimulator may communicate by various wireless means including by a radio frequency link.
The implant procedure commonly involves removing some of the bone to form a well for receiving the stimulator to assist in the security of the fixation. Additional fixation is commonly used and is achieved using sutures or biocompatible screws.
Thus, fixating cochlear implants has traditionally required that the site of fixation be completely open to allow full and unrestricted access to the site. This requires a large opening to be formed, increasing the complexity of and the risk associated with the surgery as well as increasing the recovery time of the patient.
It is therefore an object of the present invention to provide a means of facilitating the fixation of a medical implant in a patient.